Using standard methods from the theory of scattering [1]}, [2]},
we obtain an expression for the differential scattering cross-section of the
process \(I_{3} \rightarrow I_{3}^{\prime }\)  in terms of the scattering amplitude
\(f_{I_{3}^{\prime },I_{3}}\)
\(d\sigma _{I_{3}^{\prime },I_{3}}/d\theta = \left|f_{I_{3}^{\prime },I_{3}}\left(p, \theta \right) \right|^{2}. \) 
